From my air cooled VW days ( Type 3 / 4 and Porsche 914 ) , the cam in the dist for trigger points is an eccentric that fires each set of points once per dist rev.

The points are opposite each other and are there to sync the injector pulses. On a 4 cyl the injectors were fired in pairs, One fired into a closed intake valve and the other in an open one. From what I recall, 1/2 of the required fuel was inj per firing but don't quote me on that.

In any event, look around some Porsche 914, Volvo, SAAB, Jag sites as these cars used D jet.